Using Node js to build realtime android app - android

I want to develop two apps which are related to each other. One is a postman app and another is for users who want to use postman's task.
I have been using node js server which uses socketio. I want to show couple of postmans in user app which they are in location constraint (define specific treshould). When the user taps his map and changes his position, postmans location should updated in user's map and show to them.
In order to design these apps, I had two scenarios in mind.
The first scenario I had, when user changes his position send his location to server and server should get postman's location which is in my defined treshold, but I think it's not optimal because when postmans move realtime in map, server should store their location and updated them and then fetch those to show in user app.
Second one is server broadcast to all postman's app and in postman's app side check treshould and if it's true send back his location to server.
Which of them would be appropriate to develop this situation?

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Is there a push notifications api for a locations application on flutter

I'm currently working on a flutter navigation application that can enable a user to take pictures of places and store them as familiar locations and has the capacity to inform a user in case they have passed by that specific area for example a new and upcoming restaurant.
My challenge is I do not know how to use push notifications to specifically inform the user upon arriving or passing by their destination
You can use the package
https://pub.dev/packages/geolocator
This package will help you get constant location update of the user and then by using this package calculate distance between the user and the restaurant you want. Fire a local notification using the following package
https://pub.dev/packages/flutter_local_notifications
when the user passes some distance from your restaurant or when he is about to come close to that restaurant.
Hope this is clear.

Can I fetch the data being given to an app by its host and store it locally?

I would like to preface my query by saying that I am an absolute beginner when it comes to programming but I really want to realise this project so every little help is deeply appreciated.
I am trying to build an app that needs accurate train data for it to work and from my current research as there is not central government API for railway data , the only accurate data source for train location that I can find is in an other app that uses crowd sourcing to pinpoint the location.
I wanted to know if it is possible to fetch that train data from that app and then use it on my own as it would make my app a lot more reliable and accurate.
The issue currently is that the app only shows graphical representation of the data thats being fed to it from its servers , so I wanted to know if there is a way to access the actual data being sent to the app.
Thank you.
Let me clarify, this is a very broad question and hence will have a very broad answer too.
As far as I can understand from your question is that you want to show TRUE location on a map.
For this, you will have to understand the complete Tracking scenario. Let me explain it to you step-wise below:
There is an app, installed on a device (user) which fetches the GPS location (REAL) data and keeps sending it to a server (backend).
This GPS data is the Lattitude-Longitude coordinates of the device (user).
The server stores this information in their database for queries.
There is another user, different than the one currently sending the location data, who wants to know the location of the first user. The app which he is using will request the server (backend) to send the location data for the device. Which, in turn, will send the latest location data (LatLng coordinates) to the current app. This app will then show the location data over a map.
Now, usually, this process is followed to show one-to-one location data. However, in scenarios like Train Location etc, servers usually collect pool of location data, being received from several users, to cross-verify the actual location (average out, mean, location optimization algorithms etc.) and then display that information over a map.
As per your requirement, which I can understand, you want to get this REAL data directly from either another app or from the server. If you want to get the location data from the server, you will need an API, which serves as a Request-Response platform. However, if you are looking to get the data from another app, it would rather be simpler to get the location data directly, as your APP will also be installed on the device itself.
I would suggest you to kindly read about getting and processing location data, communication with servers over API etc for better understanding and implementation of your requirements.

Send request from one android app to another app using a Web server

I am doing my Semester project of Android.I am making a food delivery app.The work I have to do is that the user will send the request to a nearest restaurant.
The restaurant will accept the request and deliver the desired order that a user requested.
I know I have to work with maps and webserver.Maps will be used to get the location of the user and I am pretty good working on that.I know how to connect the android app with webserver as well.
But, I don't know how the user from his app will send request to the restaurant app by using webserver.How the resturant will accept and which restaurant will accept (in my case a nearest restaurant should accept,but first I just need to connect the user with restuarant).
Need a guide or Tutorials how I should Start this.I am really confused.
I strongly recommend you use Firebase - [https://firebase.google.com/?hl=pt-br][1] - to receive/send messages throught web. It´s very simple to use!

Making a Android chat app and finding people nearby

Hi everyone I'm in trouble one of my friends asked for a chating Android app which it could find "People Nearby" using this app and first I said yes I can make it but now I'm unable to do.
so It's my very first app that I'm making it for someone I wanted to know if "People Nearby" is simple function for an app or it's complicated and hard to make it
I've seen this kind of apps like swarm that shows you people nearby
but unfortunately I can't find any help or source or tutorial for it the only thing I could find was Google's Nearby Messages which I'm not sure that's what I'm looking for
so I would be very happy if you could help me or at least tell me where I can find a help.
Server side:
(You can use python flask for this kind of simple requirement If you do not have experience in server side scripting)
Your API's must have.
/register -> Registering user profile (unique id, name, location etc) and save it in database.
/receive_location -> Receive location (lat lang values), update in the user profile and check with all records in your database who is in the radius(defined by you or get this as from user) and return the list of user details to client.
Client side:
Have an IntentService which will post location of the client to the server at certain intervals returns the list of users who are in the radius you define.
User googleApiClient to get the location and server .
http://developer.android.com/training/location/retrieve-current.html
Use recycler view to show this result. Send a local broadcast from intent service to tell the activity containing recycler view to update it.
Basic requirement for this is you must have server where all user data is stored.
You must have all users updated latitude and longitude.
To get updated latitude and longitude you must call your api at periodic times.
If you want nearby people search you must call api with your current latitude and longitude, then from server and your api must filter all users location and gives you nearby people.

limit one area and browse other people are using the same app

When my app is triggered, it takes the current position of the user through the GPS (this function already implemented).
My question is: I want to know for example if I have users who are using my app in a given radius (1km for example). Is it possible?
Yes, but you need a server as well. Broadly speaking, the process is as follows:
The app gets the location from Android.
The app queries the server, sending the current location in its request.
The server stores the location and the user name in a spatial database; that is, a database of users that can be indexed by location. It overwrites the previous location if there was one. The server should also store the time the location was set.
The server also looks up the location in the spatial database to find all the users in the given radius, or the nearest n users. It sends the list of users back to the app. It might use JSON, XML, or some other format to send these data. (Since you control both the server and the app, you can choose whatever format you like.)
The app reports its position to the server again if the device's location changes, and gets a new list of users.
You can also use Google Cloud Messaging, or a persistent connection, to let the server notify the app when new users appear nearby, if your application needs that.
When the user goes offline, the app sends another message to the server to tell it. This erases the user's location for the database so this user won't show up after he has left the area.
The server should also delete locations from the database if they haven't been updated in a certain amount of time, in case the app crashed or got disconnected abruptly.
For the server, you can implement something on top of PostGIS, for example. PostGIS is a plugin for PostgreSQL that allows it to answer spatial queries.
This is a very specific need, so I don't think there's any existing code you can download to do this for you. Once you've tried it out, ask a new question if you get stuck.

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